Decrypt QueryString – Space + Issue = Uri.EscapeDataString

While working with encrypted querystrings in ASP.NET I noticed people doing this:

string strValues = "search term";
string strURL = "http://mysite.com?search="
+ encryptQueryString(strValues);
Response.Redirect(strURL);

string strScramble = Request.QueryString["search"];
string strdeCrypt = decryptQueryString(strScramble.Replace(" ", "+"));

The “strScramble.Replace(” “, “+”)” is a scary way to get around the request.querystring automatically changing the “+” into a space.   A better way is to use System.Uri.EscapeDataString before adding the querystring value. Then HttpUtility.UrlDecode works as expected returning the “+”.

According to this blog on MSDN (http://blogs.msdn.com/yangxind/default.aspx), when encoding the URL use “System.Uri.EscapeDataString”, when decoding the URL use “ HttpUtility.UrlDecode“.

Example using Uri.EscapeDataString and taking out replace:

string strValues = "search term";
string strURL = "http://mysite.com?search="
+ encryptQueryString(Uri.EscapeDataString(strValues));
Response.Redirect(strURL);

string strScramble = Request.QueryString["search"];
string strdeCrypt = decryptQueryString(strScramble);

NET encoding methods

There are two decoding methods in .NET